The invention relates to mass spectrometry, and particularly to mass spectrometric analysis of gaseous analyte samples containing analyte substances of interest. The invention has applicability, among other areas, to analysis of atmospheric gas samples, and to detection of gaseous substances present in trace amounts.
The presence of normal concentrations of atmospheric gases in an analyte sample can interfere with measuring trace amounts of gases of interest. For example, when analyzing an atmospheric gas sample using a mass selective detector, the large amounts of nitrogen gas present in the atmosphere will cause a large peak, with tailing shoulder. This large signal can overwhelm the signal of a trace gas that is close in molecular weight to nitrogen.
Typically, the entire gas sample enters the analyzer without any separation. However, separation of the gas sample in order to reduce the concentration of the large-quantity gas relative to that of the trace gas of interest could improve the results of the analysis.
A gas chromatograph can be used to separate the gases prior to analysis by the mass spectrometer, but this is an expensive solution and is not easily incorporated into a remote field instrument.